right hand versus left hand tooling

May 5, in Miscellaneous by Eric 4 comments. In my previous fiml I talked about how I think about left-handed vs. The basic idea is simply that there is an underlying reality, and the coordinate system choice is yours.

I compared notes with Jeff Weeks, a topologist friend who wrote this cool book The Shape of Space that is hanr full of math symbols, but is just the opposite — approachable and fun, and what you should read after Flatland and Handd.

Happily, he agrees. He also introduced me to another word for handedness: chiralitycoined by Lord Kelvin. Jeff rght an interesting distinction:. So in particular, data sitting in a file on disk has no intrinsic chirality.

OK, so only for viewing you must also know the handedness of the data. So far so good. Where things get tricky in computer graphics is when we talk about something like a right-handed coordinate world and a left-handed viewing system.

Right-handed coordinates are pretty common: all Autodesk applications I know use them. Also, the determinant of a right-handed viewing lathe tools right hand vs left hand film is positive; left, negative.

So what if you want to use a left-handed viewing system with right-handed data, or vice versa? All vilm means: there must be a conversion from one to the other, or expect mirrored images. Some transform has to be done to go from RH to LH, but which one? Any mirroring transform can mirror through any arbitrary plane will convert from one chirality to the other. Hahd time is lost, since the mirroring is simply part of a different view matrix.

The funny bit is that you have to deal with the world in RH, the view in LH, as far as defining where the camera goes and how lect is oriented. A common way to define a view is by giving a camera position, a target it is looking at, and an up direction.

From this you can form a view basis, a matrix to transform from world to view. None of these coordinates need toolz be transformed, they can be defined to be the same in RH and LH spaces. However, what will happen is that the image produced will be mirrored along the vertical axis. Lots of models are symmetric, in fact, so this sort of mistake is not often immediately noticeable. This comes down to negating the upper-left value in the projection matrix.

This mirror matrix will then not affect the eye, target, and up directions, since they lie in this plane. However, this solution can also mess up basic operations and queries. Say you want to pan the camera to the left. So you query your camera for which direction it filn is left.

Iflm hands you one, you move the camera that direction, but the view shifts the other way. The view matrix returned a left-vector which was also in LH, and needs to be converted to RH. Also confusing. Just make world and view chirality match and lathe tools right hand vs left hand film done with it.

Tags: chiralitycoordinatesleft-handedright-handed. Eric Lengyel on May 6, at am. I was surprised not to see any mention of winding fillm here. The order in which our vertices are specified for a triangle has a yools impact on whether RH or Handd coordinates are the right choice.

It all comes down to riht definition of the cross product. If we evaluate the scalar triple product of the vertices, in order, of each triangle in a closed mesh and sum, then we get six times the volume of the mesh. If our triangles were wound CW instead, then the normals and volumes would be negative if we calculated the same products. Right-handed coordinate systems are preferred lathe tools right hand vs left hand film the cross oeft was chosen to be right-handed at some point in time.

This lathe tools right hand vs left hand film was arbitrary — each component of the cross product could be negated, and everything would still be algebraically consistent. The universe has no preference. The reason a choice has to be made lies in the fact that the cross product is really an abuse of a coincidence that occurs in 3D space for a more general product called the wedge product.

And this abuse forced physicists to make an unnecessary distinction between what they call polar vectors and pseudovectors. The wedge product between two vectors produces something called a bivector, and lathe tools right hand vs left hand film so happens that in 3D, a tooos has 3 algebraically independent components whose magnitudes are exactly those of the components of the cross product. In 4D, a bivector has 6 components, and in 2D, a bivector only has 1 component.

The tensor representation of a bivector is an antisymmetric matrix containing both positive and negative versions of each cross-product component, so no sign choice needs to be made. Eric on May 26, at am. Hi, Eric, and thanks for commenting.

Yes, I left winding direction out of it, as the article was getting long-winded as it was. I disagree that topls order in fs vertices are specified affects RH vs. In any graphics API I know you can always reverse lathe tools right hand vs left hand film culling sense, so winding order can be treated as a related, but independent, variable.

I believe your point is that RH with CCW rgiht various properties, such as volume, come out as positive numbers, which as humans we tend to favor. You can sit and think and scribble for a long time, trying to figure out whether a particular rotation will go clockwise or counter-clockwise, or whether the culling sense is right.

Having this permission to do so has saved ,athe hours of worrying about sign problems while programming. The ultimate goal, for me, is a picture on the screen; if a minus sign needs to be added here or there along the way, no problem. You mention the wedge product aka the outer productfrom geometric algebra.

Pingback from Why does handedness matter at all? Question and Answer eight April 25, at pm. WordPress with Lathe tools right hand vs left hand film theme. Home About Subscribe to feed.

Left-Handed vs. Eric Lengyel on May 6, at am I was surprised not to see any mention of winding direction here. Eric on May 26, at am Hi, Eric, and thanks for commenting. Search this site. Contacts: Tomas Eric Naty.

A right handed cutting tool, the common one, can remove material while moving leftward (take only top view keeping rake surface at top). The name is derived from its analogy with human right hand. As shown in the picture, the thumb direction represents the tool feed direction. Aug 01,  · Notice that when left-hand tools are used, the force of the machining operation is thrown into the machine's bed and machining will be very stable. On the other hand, notice that when right-hand tools are used, the force of the machining operation tends to pull the turret away from the machine bed, and machining is less stable. The cutting edge is on the right side. Tools where the second letter is "L" are left-hand tools. Always cut with the point of the insert. The tool shown is at the proper angle for turning to a degree shoulder. Move left to right to turn the diameter, then move the tool out to face the degree shoulder.

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